The pattern behind Sunday morning's serial blasts in Bodh Gaya is now clearer, but the investigators' frustration in not being able to secure leads from this pattern continues. The investigators have now established that all cylinders used in the blasts were new and locally made and all shopkeepers selling them within 100 km are being identified and questioned.

But a bomb placed at a height of 20 feet on the Buddha statue has troubled investigators. They believe a ladder must have been used by terrorists. The fact that a ladder was present inside but it's absent now has confounded them.

On Tuesday, anti-terror teams from Maharashtra, Andhra Pradesh and Uttar Pradesh joined the probe in Bodh Gaya. Even as the questioning of a man whose identity card was found close to the blast site continued, officers say they are almost certain he had no role.

The NIA and Bodh Gaya Police have also taken CCTV footage from hotels and guest houses in Bodh Gaya besides seizing registers of guests from over 200 such premises and are questioning hotel managers on suspicious check-ins and exits.

Differences, however, have cropped up between the NIA and the Bodh Gaya Police on the quality of CCTV footage from the temple complex. The NIA maintains the CCTV footage does not reveal much and even said they believed the terrorists were aware of their exact location and hence have managed to evade the cameras, which is a view not shared by the Bodh Gaya Police.

Investigators are also interrogating each of the 40 private security guards and housekeeping employees deployed at the temple complex with a specific emphasis on personnel on duty the night before the blasts. Analysis of cell phone calls made before and after the blasts have so far not yielded substantial leads.